Bearings are often incorporated into molded plastic pulleys, which are commonly used in drive belt applications, such as serpentine drive belt systems for driving front end accessories in/on a vehicle engine. Typically, a plastic pulley body is over-molded to the bearing. Changes in speed, load, and temperature can cause an outer race of the bearing to rotate (slip) relative to the plastic pulley shell. Seal drag from the bearing, grease viscosity, and roller contact (impacted by ball, cage and raceway design) can also impact an amount of torque back to the pulley.
Additionally, variations in temperature of the pulley system can impact slipping or rotation of the pulley relative to the outer race of the bearing. Bearings are typically constructed of metal, which has a different coefficient of thermal expansion than the plastic of the over-molded pulley. The difference in coefficients of thermal expansion between the bearing and the pulley shell can reduce the clamp load force applied by the molded pulley back to the bearing outer race. A reduction in the clamp load force reduces the frictional forces acting between the bearing and the pulley shell. As the system load increases, the plastic pulley shell tends to pull away from the bearing outer race, which leads to slippage or rotation of the pulley shell relative to the bearing outer race. Some bearings include keyways or knurl patterns to prevent slippage, but these bearings are typically very expensive. Therefore, there exists a need in the art for a cost-effective solution that may substantially prevent slippage between an over-molded plastic pulley shell and a bearing outer race.